Lummi Nation Nooksack River Basin Salmonid Population Assessments, FY21

Two rotary smolt traps were operated in the Nooksack River, one in the lower mainstem (which had been operated since 1994) and one in the South Fork. The additional smolt trap in the South Fork expanded our ability to calculate outmigration survival and expanded mark/recapture estimates based on PIT tagging data. Fishery biologists and technicians operated both traps during the principal outmigration period from approximately January to August. Additional beach seine sampling near the lower mainstem trap site was conducted to improve smolt production estimates and sample a wider spectrum of outmigrant size classes. This additional sampling also helped improve sample size for DNA collection to enumerate differences in population and origin productivity (i.e. Hatchery vs. wild origin; North Fork/Middle Fork vs. South Fork population). Production estimates were made for Chinook, Steelhead, Coho and other salmonids from modeled expansion of trap catches.

The goal of this project is to improve the quality and accuracy of salmonid escapement, production, and habitat use with a focus on Chinook. A secondary goal is to identify constraints preventing recovery of the stocks. This work is to evaluate and adaptively improve methods for salmonid population baseline data acquisition and estimates required for: 1) ESU reporting, 2) forecasting/management, 3) stock identification and aging, 4) evaluation of survival, restoration, and hatcheries, 5) other research including impacts of climate change or identifying limiting factors. A secondary objective is to utilize these data in a life history model and framework for Nooksack early Chinook, which is currently in development (funded separately).



The expected benefits of providing more accurate and complete population estimates and habitat use for adults and juveniles are: 1) evaluation and identification of restoration activities that will have or could have the largest impact on recovery, 2) improved ability to identify factors limiting recovery, such as predation or toxicity that habitat restoration cannot address and that may require other actions or solutions.